Logo appears in http in the code instead of https

Hi,

My site doesn't appear as secured in https because an image would still be in http. I use iThemes Security to force the redirections. The host advised to empty the cache or modify the theme. Cache didn't change anything. Theme is Pixel and a child theme. I also use Polylang plugin. The image seems to be the logo. Here is the code of the page where I found the problem:

</header><!-- #masthead -->
<nav id="mobile-header" class="main-navigation mobile-header-navigation has-branding" itemtype="https://schema.org/SiteNavigationElement" itemscope>
		<div class="inside-navigation grid-container grid-parent">
			<div class="site-logo mobile-header-logo">
				<a href="https://mysite.org/" title="my site" rel="home">
					<img src="http://mysite.org/wp-content/uploads/2020/03/logo.png" alt="my name" />
				</a>
			</div>

In the backend, where media are, the logo path is in https. I really don't understand why it appears http on the front.

Any idea?

Thanks